(1) Field of the Invention
The present invention relates to a laser projection display device that scans a laser beam from a semiconductor laser with a two-dimensional scanning mirror or the like to display an image and a driving method for a laser beam source used therein.
(2) Description of the Related Art
In recent years, a laser projection display device which projects an image with a semiconductor laser, a MEMS (Micro Electro Mechanical Systems) mirror, and the like has been made practicable. This laser projection display device is used as, for example, a head-up display for driving support for an automobile. In the laser projection display device, a two-dimensional scanning mirror horizontally and vertically scans, and, at the same time, a laser beam source is modulated to display a desired image on a projection surface.
For example, Japanese Unexamined Patent Publication No. 2006-343397 (Patent Literature 1) describes a configuration in which, in an image projection device which raster-scans a laser beam to project an image on a screen, the emission intensity of a laser beam is adjusted in accordance with a change in horizontal raster scanning speed such that the brightness of a projection image displayed on the screen becomes uniform.
Japanese Unexamined Patent Publication No. 2003-85845 (Patent Literature 2) includes, as a problem to be solved, a phenomenon in which, in a pulse drive magnetic modulation overwrite type magneto optical recording/reproducing device, when a laser beam source is driven with a rectangular pulse, a laser emission waveform is overshot and vibrated at a rising edge of each pulse. Patent Literature 2 describes, as a countermeasure against the problem, a configuration in which a laser beam is preliminarily emitted before the emission intensity of the laser beam is increased to a recording power level as long as the laser beam does not influence a recording film of a recording medium although the laser beam is emitted.